Whenever one of your opponent’s non-unique units in this arena attacks, that unit gets Accuracy -1 for that attack unless your opponent pays 1 Force.
Keywords
Accuracy
Accuracy X/-X: A cumulative, static ability that means, "Add X to each of this unit’s attack dice." and "Subtract X from each of this unit’s attack dice." respectively. Accuracy can’t alter "natural" rolls to affect Critical Hit, Fury, or Parry, but it can affect your chance against Armor. If a unit gets the Accuracy ability after you roll attack dice, it's too late to affect the hits.